Download either the latest 32-bit build or 64-bit build and extract the contents of the bin folder (ffmpeg.exe, ffplay.exe, ffprobe.exe) to a location on your system. You may want to make the path short for simplicity (e.g. C:\ffmpeg).

Optionally, add the path to ffmpeg.exe to your system path so you can run it without the fully qualified path.

Then you can call it similarly to how you would on linux in PHP with exec() or system().